The invention relates to the field of self-refrigerating systems employing evaporation/condensation processes. Specifically, the invention relates to those self-refrigerating systems useful for the chilling of portable and/or disposable liquid containers.
There are many foods and beverages that can be stored almost indefinitely at an average ambient temperature of approximately 20xc2x0 C.-25xc2x0 C. but that have more favorable properties when cold than when at ambient temperature. Electrically powered refrigeration units can cool these foods and beverages. The use of these units to cool foods and beverages may not always be practical because the units require a source of electricity, are not usually portable, and may not cool foods and beverages quickly.
Alternatively, phase change materials such as ice can cool foods and beverages. Such phase change materials may not always be available, and may not cool food or beverages sufficiently quickly. Using ice to cool foods or beverages may be undesirable because ice can be stored for only limited times at temperatures above 0xc2x0 C. Additionally, a beverage can be undesirably diluted by ice that melts while cooling the beverage.
An alternate method for providing cooled food or beverages on demand is to use portable insulated containers. These containers typically only function to maintain the temperature of the food or beverage placed inside them and usually require ice to achieve a cooling effect. These containers can be bulky and heavier than the food or beverage being cooled, especially when used in conjunction with ice. Moreover, ice may not be readily available when a cooling effect is desired.
In addition to cooling food and beverages, there are other applications for which portable cooling devices may be desirable. These include: medical applications, such as cooling of tissues or organs, preparing cold compresses, and cryogenically destroying tissues as part of surgical procedures; industrial applications, such as producing cold water or other cold liquids upon demand, preserving biological specimens, cooling protective clothing; and various cosmetic applications. A portable cooling apparatus could have widespread utility in all these areas.
Some attempts to build a self-contained miniaturized cooling system have depended on the use of a refrigerant liquid stored at a pressure above atmospheric pressure, so that the refrigerant vapor could be released directly to the atmosphere. Unfortunately, many available refrigerant liquids for such a system are either flammable. toxic, harmful to the environment, or exist in liquid form at such: high pressures that they represent an explosion hazard in quantities suitable for the intended purpose. Conversely, other available refrigerant liquids acceptable for discharge into the atmosphere (such as carbon dioxide) have relatively low heat capacities and latent heats of vaporization. As a result, some cooling systems which release carbon dioxide are more bulky than is commercially acceptable for a portable system.
An alternate method known in the art for providing (a cooling, effect in a portable device, for example, a beverage can is to evaporate refrigerant in a first chamber and absorb or adsorb the resultant refrigerant vapor in a second chamber. In such a system, liquid refrigerant boils under reduced pressure in the first chamber, absorbing heat from its surroundings. The vapor generated from the boiling liquid is discharged into the second chamber, which contains a desiccant that absorbs the vapor and the heat.
A particular self-refrigerating device that can be used in con unction with the present invention includes three basic sections: an evaporator initially containing a refrigerant, an absorber initially containing a desiccant, and a means to prevent the inadvertent flow of refrigerant vapor between the evaporator and the absorber. This flow-preventing means is also adapted to allow the flow of refrigerant vapor between the evaporator and absorber when, for example, the device is in operation. The functional relationships between these sections have been described in U.S. Pat. Nos. 5,197,302 and 5,048,301, which are incorporated by reference in their entirety.
The configurations which have been available to this point for the cooling of liquids with self-refrigerating systems show that a simple scale up of a single serving system would not function as desired for an application intended to cool a large volume of fluid. The cooling of large volumes of aqueous liquids takes a relatively long time. This delay can be inconvenient for consumers wishing a portion of cold product sooner than it takes to cool the entire volume of product.
The present invention provides a portable, single-use disposable system for the cooling and dispensing of products. This cooling and dispensing can be implemented by adapting a conventionally manufactured product container to allow the contents of the container to come into contact with a cooling surface of a disposable refrigerator for a time sufficient to cool an internal reservoir portion of the container volume. Alternatively, a system can be fabricated independently of any existing container, and a container can be specifically built for that system. A cooled portion from the internal reservoir can be subsequently dispensed for use. The invention is born out of the recognition that a simple scale-up of conventional self-refrigeration systems does not provide a way to cool a fractional portion of a relatively large volume of product for use on a short time scale without cooling the entire volume. Thus, the invention provides a method for cooling fractions of a large product volume as they are needed.
Refrigerators which can be used in the present invention generally have a fixed ability to absorb heat. If the maximum heat is not provided all at once, the refrigerator idles at a minimum temperature near, but above, the freezing point of the refrigerant. As heat leaks in, the refrigerator can absorb the heat and maintain a minimum temperature. The current invention involves a flow-through system, whereby a product passes through an internal reservoir space before it is dispensed. This internal reservoir space has the capability of cooling the product to a low temperature.
In one aspect a disposable refrigeration system is disclosed for cooling and dispensing a product. The system includes a flow-through refrigeration system that includes an evaporator chamber containing a refrigerant that, during operation of the system, evaporates to form a vapor, an evacuated absorber chamber including a sorbent for receiving the vapor and a heat sink material in thermal contact with the sorbent, a means for preventing the flow of vapor from the evaporator chamber into the absorber chamber until commencement of operation of the refrigeration systems a primary volume of dispensable product, a product reservoir in fluid communication with the primary volume of product containing a secondary volume of product, and a dispensing means allowing controlled withdrawal of the secondary volume of product contained in the reservoir. The reservoir includes a flow path from the primary volume of product to the dispensing means, and at least one wall of the flow path is in thermal contact with an outer surface of the evaporator chamber during operation of the refrigeration system. The product may be a liquid. The liquid may be a potable liquid, which may be a carbonated beverage. The refrigerant may be water. The refrigerant may be supported by a hydrophilic, gel-forming polymer. The means for preventing flow of vapor may include a frangible seal and an actuator. The sorbent may be an aluminosilicate zeolite. The heat sink material may be a phase change material, which may undergo a phase change at a temperature between about 50xc2x0 C., and about 75xc2x0 C. Fluid communication from the primary product volume to the product reservoir can be accomplished through gravity feed.
Another aspect includes a method of cooling a dispensable product. The method includes providing a refrigeration system that includes a flow-through refrigeration system. The flow-through refrigeration system includes an evaporator chamber containing a refrigerant. The refrigerant, in operation of the system, evaporates to form a vapor. The flow-through refrigeration system also includes an evacuated absorber chamber including a sorbent for receiving the vapor and a heat sink material in thermal contact with the sorbent, a means for preventing the flow of vapor from the evaporator chamber into the absorber chamber until commencement of operation of the refrigeration system, a primary volume of dispensable product, a product reservoir containing a secondary volume of product, the product reservoir being in fluid communication with a primary volume of product and a dispensing means allowing controlled withdrawal of the product contained in the reservoir. The reservoir includes a flow path from the primary volume of product to the dispensing means, and at least one wall of the flow path is in thermal contact with an outer surface of the evaporator chamber during operation of the refrigeration system. Operating the means for preventing the flow of vapor from the evaporator chamber to the absorber chamber, can allow the flow of vapor between the evaporator and absorber chambers. The refrigeration system can remove the vapor from the evaporator chamber and receive the vapor in the absorber chamber, thereby cooling the secondary volume of product contained in the reservoir. The method may also include dispensing the secondary volume of product by operating a dispensing means. The method can also include refilling the product reservoir by transferring product from the primary volume to the product reservoir. The method can also include transferring a product from the primary volume to the product reservoir by gravity feed.
The invention provides a self-contained and disposable refrigeration system. The system does not typically vent a gas or vapor of any kind. There are no hazardous or toxic materials or components included in the system, and recycling of the materials of the system is facilitated. There are no pressurized gases present in the system and no environmentally objectionable materials such as unstable refrigerants. The system does not explode, even when consumed by fire, and is not flammable.
The refrigeration system can provide cooling of a product having a relatively large volume. In the case of a liquid product, the volume can be at least one liter, and as much as several hundred liters. This aspect of the invention finds utility in the cooling of potable liquids, such as beverages which are preferably consumed at temperatures lower than ambient. Such beverages include soft drinks, milk, water, fruit juices, certain wines, beer and similar beverages. The portable and disposable nature of the system can make it ideal for providing cooled products in locations which are remote from sources of electricity or auxiliary coolants such as ice, or in locations where ice is difficult to transport conveniently.
The invention provides a refrigeration system which can be easily adapted to an existing product container without a re-engineering of the container. By cooling a fractional portion of the product, rather than the entire primary product volume, a consumer can be more effectively served. Also, insulation of the entire primary product volume, to minimize heat leakage back into the product from the surroundings, may be prohibitively expensive. Insulation of the present system, if needed, can be limited to the internal product reservoir.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the present inventions suitable methods and materials are described below. All publications patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.